A tachograph file is invalid when its signatures are broken.
This often means there is a problem with the tachograph itself. To find and fix the problem, the repair center needs to see the file that the tachograph created.
That is why you can download invalid files from remote downloads, one file at a time.
Bring the file to your repair center, so they can find out why the tachograph creates invalid files.
⚠️ Invalid files are not compliant.
Do not use them as an official record, for legal or compliance reporting, or for data analysis. Only use them to find and fix the problem with the tachograph.